Nematic liquid crystals confined to supramicrometer capillary tubes with homeotropic anchoring conditions are studied using optical polarizing microscopy. The resulting microscopy textures are sensitive to the molecular anchoring strength ${\mathit{W}}_{\mathrm{\theta }}$ and the saddle-splay surface elastic constant ${\mathit{K}}_{24}$. These two quantities are determined by comparing the observed textures of the escaped-radial nematic director field to simulated textures predicted from Frank elastic theory and considering the stability ranges of other possible structures.

• Received 13 October 1993

DOI:https://doi.org/10.1103/PhysRevE.49.R978